This invention relates to a unitized single line (pressure-vacuum) pneumatic tube system capable of incorporating intermediate stations, and novel components therefor.
Traditionally, pneumatic tube systems which deliver carriers to one or several locations and back have been custom designed, requiring extensive engineering and selection of various components. Single line pneumatic tube systems are well known in the prior art as exemplified by U.S. Pat. Nos. 2,137,750 and 3,232,559 and are utilized for drive-in banking and tolls as shown in U.S. Pat. Nos. 3,599,898 and 3,976,264. Such systems normally use a high powered turbine to provide the necessary air; however, the noise level of the turbine is such that the turbines are located at a remote location from the terminals. Moreover, the air shifter valve for such a system is usually complicated and changes the direction of flow causing turbulence. Although some single line systems do use smaller blowers, they require a blower at each terminal location.
Accordingly, a need has existed for a unitized system which can be packaged and sold by the manufacturer as a complete system eliminating custom design. Also, there is a need for a simple single line pneumatic tube system having a single power unit which is sufficiently quiet that it can be installed in a room where people are working. There is also a need for an air shifter which eliminates changing direction of the air. Further, there is a need for a single line pneumatic tube system which has a minimum of noise at the end terminal and which can include intermediate terminals which can transmit a carrier in either direction without complicated valving.